Preparation of substituted dioxepins



United States Patent PREPARATION OF SUBSTITUTED DEOXEPINS George B.Sterling, Midland, Mich, Edward J. Watson,

Norwich, N.Y., and Chester E. Pawloslri, Bay City,

Mich, assiguors to The Dow Chemical Company, Midland, Mich, acorporation of Delaware No Drawing. Filed Jan. 3, 1961, Ser. No. 80,0216 Claims. (Cl. 260-338) The present invention relates to the preparationof substituted dioxepins and is more particularly concerned with thepreparation of 1,3-dioxepins by the single exchange reaction between2-butene-1,4-diol and a dial koxy compound such as an acetal or a ketal.

We have found that substituted l,3-dioxepins may be convenientlyprepared in high yield and purity by reacting 2-butene-1,4-diol with anappropriate dialkoxy compound, e.g. an acetal or a ketal, in thepresence of an acid catalyst and at a temperature of from about 20 toabout 100 C., preferably at room temperature or slightly above.

3,116,299 Patented Dec. 31, 1963 moles (546 grams) of2,2-dimethoxypropane, and a few drops of concentrated sulfuric acid wereplaced in a 2 liter flask. An endothermic reaction resulted in theformation of a single liquid phase in the flask. The mixture was thendistilled at atmospheric pressure (2/1 ratio) until the head temperaturereached 62 C., after which distillation was continued under vacuum. A63% yield of 4,7-dihydro-2,2-dimethyl-1,3-dioxepin was obtained boilingat 41 C. at 6.0mm. of mercury pressure absolute.

EXAMPLE 2 The above experiment was repeated using 1640 grams (10 moles)of 2,2-dimethoxypropane. The yield of product was 74%.

EXAMPLE 3 In a manner similar to that of Examples 1 and 2, the acetalsand ketals listed in the following table were reacted with2-butene-l,4-diol. The product, yield, and product boiling point aregiven in the table.

Table 1 Per- Run Acetal or Ketal 1,3-Dioxepin cent B.]?., C.

Yield Dirnethoxymethane 4,7-dihydr0- 4 124 C.760 mm. Dimcthoxybutane2-ethyl-2-rnethyl-4,7-dihydro-, 38 101 C.-89 mm.

. Diethoxypropane 2,2-dirnethyl-4,7-dihydro- 46 41 C.6 mm.Dibutoxypropane d0 50 41 0-6 mm. Z-butoxy-fbrnethoxy propane d0 53 41C.-6 nun. 2,2-dimethoxy-1-bromopropane ablngmgmethy-2-methyl-4,7- 68. 5116 G.10 rum.

1 y ro-.

1,1-diethoxyethane 2-methyl4,7-dih vdro 53 137138 (1-760 mm.l,l-dimethoxy-eyclohexane 7,l2-dioxospiro-[5.6] d0dec-9-ene. 88 54O.-0A. mm. a,a-di1neth0xy toluene 2-phenyl-4,7-dihydro 55 79 (1-0.6 mm.

The reaction is illustrated as follows:

wherein R and R represent individual members of the group consisting ofalkyl and halosubstituted alkyl groups containing up to 9 carbon atoms,aryl and haloaryl groups of the benzene series, alkenyl groupscontaining from 2 to 9 carbon atoms, hydrogen, and cyclizing linearpolymethylene units containing 2 to 3 carbon atoms; and R and Rrepresent alkyl groups containing up to 9 carbon atoms.

Suitable acetals and ketals include, for example, 2,2-dimethoxypropane;2,2-dimethoxybutane; 3,3-dimethoxypentane; 2,2-dibutoxy propane;2-butoxy-2-methoxy propane; 2,2-dimethoxy-3-bromo-propane;1,1-diethoxyethane, dimethoxy cyclohexane; a, x-dimethoxy toluene andthe like.

Approximately equimolar proportions of the butenediol and the acetal orketal may be employed although for best results approximately twice asmuch ketal or acetal, molar basis, should be used.

Any non-oxidizing acidic catalyst may be employed, such as, for example,sulfuric acid, dichloroacetic acid, phosphoric acid, trichloroaceticacid, dichloropropionic acid and the like.

The following examples further illustrate the present invention but arenot to be construed as limiting.

It is thus apparent that a wide variety of substituted dioxepins may beprepared in good yield and purity by the single exchange reaction of2-butene-1,4-diol with an acetal or a ketal.

What is claimed is:

1. A method for preparing a substituted 1,3-dioxepin having the formulawhere R and R have the meaning given below, which method comprisesreacting 2-butene1,4-diol with a dialkoxy compound selected from thegroup consisting of acetals and ketals having the formula:

2. Method of claim 1, wherein a stoichiometric excess of the dialkoxycompound is employed.

A 0: 3. Method of claim 1, wherein the reaction is carried with1,1-dicthoxyethane in the presence of a non-oxidizing out at between 20C. and 100 C. acid catalyst.

4. Method of claim 1, wherein the dialkoxy compound Ref no C'LII th filefth t t is 2,2-dimethoxypropane. are c S 1 D m e 0 15 Pa en 5. Method ofclaim 1, wherein the dial'koxy compound 5 UNITED STATES PATENTS is2,2-dimethoxy-3-bromo propane. 2,071,252 Carothers Feb. 16, 1937 6. Amethod for preparing 2,2-dimethyl-4,7-dihydro- 2,110,499 Carothers May8, 1938 1,3-dioxepin which comprises reacting 2-butenc-1,4-diol2,341,306 Agre et a1. Feb. 8, 1944

1. A METHOD FOR PREPARING A SUBSTITUTED 1,3-DIOXEPIN HAVING THE FORMULA